First, congratulations on the new 275 I hope you are as happy with yours as we are with ours. The F-350 is a great combo with this boat.
I was told that the only advantage of the Raymarine E series in the 275 application was the increased processing power and better resolution on the screen. Negatives were the complexity of the interfacing and additional cost. Since you don't need multiple displays the multi display feature is not an advantage. I have the C120 and am happy with the display in direct sun light and with the refresh rate. One word of warning, no matter which system you choose, Yamaha does not support bi-directional communications on NEMA 2000 with the F350. My installer had a very hard time getting all of the engine related functions to display and retain the consumption calculations. Also the F-350 has no mechanical speed pick up so you must get your speed signal from the GPS and if I am not screwing this up it must come from the older NEMA protocol not from NEMA 2000. Make sure you address this issue with your installer, don't assume like I did that the Yamaha and Raymarine interface is all worked out with the NEMA 2000 protocol.